<?php
/**
 * Slipstream :: Highly adaptive dependency injection framework
 * Copyright 2010-2011 Ian Unruh (Xerof3ar)
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
namespace Slipstream\Infrastructure\Context\Relevance;

use Slipstream\Configuration\ContextInterface;
use Terrafirma\Comparator\ComparatorInterface;

/**
 * Comparator that compares the weight of two contexts in terms of a target
 * context
 * 
 * @author Ian Unruh (Xerof3ar) <ianunruh@gmail.com>
 * @since Class avaliable since release 1.0
 */
class WeightComparator implements ComparatorInterface
{
	/**
	 * @var AnalyzerServiceInterface
	 */
	protected $relevanceAnalyzer;
	
	/**
	 * @var ContextInterface
	 */
	protected $targetContext;
	
	/**
	 * Class constructor
	 * 
	 * @param AnalyzerServiceInterface $relevanceAnalyzer
	 * @return void
	 */
	public function __construct(AnalyzerServiceInterface $relevanceAnalyzer)
	{
		$this->relevanceAnalyzer = $relevanceAnalyzer;
	}
	
	/**
	 * Compares a left value to a right value and returns an integer comparison
	 * 
	 * @param mixed $left
	 * @param mixed $right
	 * @return int (-1 = less than, 0 = equal, 1 = greater than)
	 */
	public function compare($left, $right)
	{
		$leftWeight = $this->relevanceAnalyzer->getWeight($left, $this->targetContext);
		$rightWeight = $this->relevanceAnalyzer->getWeight($right, $this->targetContext);
		
		return ($leftWeight == $rightWeight ? 0 : ($leftWeight > $rightWeight ? 1 : -1));
	}
	
	/**
	 * Sets the target context that relevance weight will be in terms of
	 * 
	 * @param ContextInterface $targetContext
	 * @return vodi
	 */
	public function setTargetContext(ContextInterface $targetContext)
	{
		$this->targetContext = $targetContext;
	}
}